1. Field of the Invention
The present invention relates to an improvement in a back support system that establishes a desired postural position by creating specific sacral pressure and to apparatus that will properly position the sacrum, the pelvis, including the iliac crests, and the supporting neuro-musculo-skeletal system to produce total pelvic stability.
2. Description of the Prior Art
Back pain, in concept and in fact, is not only prevalent in society but is an area of much research and patent activity. Back pain is something many individuals experience at work, at home, and during the trip therebetween. Back pain has many causes, but few cures. The latter is not for a want of trying. Rather, patents on a wide variety of back supports or support systems abound.
For example, the patents can be generally divided in groups including those relating to seat developments, sacral or lumbosacral braces, fixed cushions or supports, and inflatable devices.
The seat development area can be further subdivided into built-in supports, add-on supports, orthopedic seats, back rests, and office chair designs.
Prior to a summary review of these prior efforts, it should be understood that non-pathogenic back pain usually results from the presence of stress on the pressure on the neuro-musculo-skeletal system and affected interrelated anatomical structure. Sometimes that stress or pressure is generated internally within the spinal cord. In either case, the resulting stress can be due to inappropriately applied pressure or due to a distorted or damaged spinal column that has existed for varying periods of time, with resulting pain depending on the prior state of the spinal cord. Consequently, in many situations the neuro-musculo-skeletal system can be supported to either relieve or prevent development of unwanted and undesirable spinal pressure.
An early spine support device is described in Epstein, U.S. Pat. No. 1,667,626. A wooden frame is used to mount a series of spring bands that form a curved face. A batting material fills the space between vertical braces and the whole device was covered with fabric. Using adjustable hooks the device was adjustable to accommodate different sized persons. The device has a width about equal to a person""s back and is shown being positioned in the lumbar region to provide uniform support over a broad region.
The built-in devices are exemplified by Sopko, Jr. U.S. Pat. No. 3,145,054 and Burton, U.S. Pat. No. 3,501,197. Sopko relates to a portable chair that incorporates a contoured pneumatic cushion which applies pressure to the posterior surface, in the sacroiliac area, and varies the pressure by forward and rearward movement of the occupant against the back supporting pneumatic cushion.
Burton attempts to restrict the body""s movement into the back/seat junction area, where the ischial tuberosities of the pelvic girdle wedges into this back/seat area, by incorporating a rigid back/seat element into the seat to prevent such wedging.
The add-on devices include a variety of devices as shown in U.S. Pat. No. Weinreich 4,753,478; U.S. Pat. No. Quinton et al. 4,718,724; U.S. Pat. No. Baxter et al. 4,516,568; U.S. Pat. No. Scott 4,634,176; and U.S. Pat. No. Pasquarelli 2,831,533.
Each of these devices includes a portion that extends across the entire back of the person as seated in the seat. In Weinreich the support is in the form of a pair of tubular cushions. Quinton et al. suggest that it had proved difficult to standardize the location of lumbar support cushions and thus developed a vertically adjustable lumbar support cushion. Baxter et al. disclose a multi-compartment air bladder, including side and center sections, so that air pressure can be applied on selected lumbar and sacroiliac areas of the body. Scott is also a vertically movable back support but has a greater area than that to Quinton et al. Pasquarelli discloses use of a dorso-lumbar curve support in the form of an elongated cushion that applied pressure across the full width of the person""s back.
The lumbosacral braces include Rowe, U.S. Pat. No. 4,930,499; Brooks et al., U.S. Pat. No. 4,475,543; Hyman et al, U.S. Pat. No. 4,576,154; Carabelli, U.S. Pat. No. Des. 296,930; and Lampert, U.S. Pat. No. 2,554,337.
Several patents disclose use of a fixed cushion. These include Parrish, U.S. Pat. No. 4,876,755; Snyder et al, U.S. Pat. No. 4,522,447; and the Meares design patent, U.S. Pat. No. Des. 277,316. The cushion used by Parrish is shaped as a capital xe2x80x9cIxe2x80x9d and supports the cervical, thoracic and lumbar regions. Snyder et al. designed foam cushions with segments having varying degrees of elasticity to provide inversely proportional support for both seating and backrest surfaces with the softest material provided where pressure would be highest.
Meares shows a design for an orthopedic device that provides full sacral pressures. The design patent does not explain how this device works or functions. However, an associated instruction book explains that the device is to be used by a person primarily in a horizontal condition. The device, while constructed from rubber in soft foam rubber, has a hollow interior and the edges are stiffer due to the presence of sidewalls that surround the hollow interior. Thus, the resistance provided by the Meares device is not uniform. The center is softer than the peripheral edges.
To use the device while lying on the floor, the device is placed on the floor and the user then rolls over onto the device. The instructions explain that the device has a wide end and a narrow end with the wide end being positioned so that it points toward the head. When one first gets on the device, the knees are to be bent and the tail bone is to be rocked down toward the floor. This movement is claimed to help position the curve of the sacrum (tailbone) into the curvature or cradle formed in the device.
As shown in the design patent, the device includes two raised portions on the anterior surface and a flat rear or posterior surface. Because the device is molded from soft rubber, and has a hollow interior, a wider cradle area is formed between the two raised areas.
The Meares device is about 7.25 inches long and has a width of 2.75 inches at the top and about 1 inch at the bottom. The upper raised area extends for about 2 inches, the cradle area then extends for another 3.25 inches with the lower raised portion extending for about 0.75 inches. Thereafter the device slopes toward the narrow end. The device should be used on a firm surface and the instructions suggest that a book could be used if the person was bedridden or a piece of plywood could be positioned under the hips to provide the feeling of a firm support.
The Meares instruction materials also state that his device can be used in a car, truck or a straight back chair. To use the Meares device in such a situation the rubber device is bent into a curved shape and then it is placed both under and slightly behind the person. The instructions also state the seat cushion is soft, a bendable book could be inserted under the rubber device to increase lift. The bent member should cradle the sacrum as when the device was used on the floor.
Thus, Meares suggests, indeed requires, full sacral pressure that is not adjustable with respect to the intensity of pressure being applied. Meares preference is to create constant pressure while the user is in a supine position.
It is also important to note that Meares isolates pressure along the full length of the sacrum. This is intended to provide a treatment to an injured set of muscles, with the piriformis and psoas muscles being of primary concern. Meares"" desire is to literally move the whole of the sacrum upwardly (when lying downxe2x80x94movement is toward one""s front). If the sacrum can be moved that way, and the hips are allowed to move in the opposite direction, that is, in a sense, to fall downwardly over the sides of his device, both the piriformis and psoas muscles will be stretched to relieve muscle spasms.
To gain an appropriate understanding of the utility and effect of the present invention, it is important to first understand the skeletal features of a human body, as well as how such features interact and affect one another. In that regard, reference will be made to the entire neuro-musculo-skeletal system of the human anatomy, as well as the interaction between those anatomical systems.
In a normal person, the spine, when viewed from the front, preferably will form a relatively straight vertical line. The function of the spine is in part mechanical, since it supports the body from the waist up, and in part protective, since it protects and houses the central nervous system or spinal cord. The spine is comprised of seven cervical vertebrae, twelve thoracic vertebrae and five lumbar vertebrae. Below the lumbar vertebrae is the sacrum and below that the bones that form the coccyx. The upper one third of the sacrum is an area identified as the sacral base.
The cervical or upper portion of the spine generally curves forward as a smooth and flexible xe2x80x9cCxe2x80x9d shaped element which supports the head and a percentage of body weight. This upper portion, because of its high flexibility, allows for rotational movement as well as fore and aft movement.
The thoracic portion of the spine, sometimes referred to as the middle back, will curve in the opposite direction, that is, rearwardly and then forwardly again. The thoracic portion supports the rib cage and the upper body portion above that area. Because the ribs are connected to the thoracic portion of the spine, the ribs themselves prevent the thoracic spine region from being as flexible as the cervical portion, and in fact, make the thoracic portion relatively rigid.
The next portion of the spine, the lumbar region or lower back, again curves in the opposite direction from the curvature of the thoracic portion. The sacral and coccyx portions extends therebelow and again curves forwardly. The lower back portion is supports the major portion of the upper body and, consequently, is under more compressive stress than the remaining portions of the spine.
The most normal curves of the spine are developed when the human body is standing in an upright manner and exhibiting good posture. As the body undergoes changes when getting into a seat and when seated, especially if one is to perform functions while in a seated position, the normal curvature of the spine is generally distorted. This is due to the fact that many, if not most, chairs do not give good spinal support. Consequently, backaches or stresses develop during sitting, especially during extended periods of sitting. Such extended sitting can create aches, soreness and disfunction.
This is true for the common man as well as in specialized instances, such as when race drivers must remain seated in the one position for hours at a stretch.
Thus, one of the principal objectives of the present invention is to support the lumbar lordosis of the spine in a shape similar to the shape found in a normal standing posture, and to provide this support when the individual is seated. One objective of the present invention is to support, principally, the sacral base. The goal is to prevent muscles from spasming by providing support and thus reducing the likelihood of muscle fatigue.
In Bridger, U.S. Pat. No. 3,740,096, there was a recognition that abnormal strains of the spine can be reduced if the occupants weight is distributed throughout each disc and vertebrae in the spine evenly so that a mechanical balance is created between the related antagonistic muscle groups and ligaments. While Murrow, U.S. Pat. No. 4,489,982 and Dunn, U.S. Pat. No. 5,114,209, recognized the importance of correct posture when sitting, they suggested use of full width back or lumbar supports. Neither recognized the importance, or even the desirability, of localized pressure, especially to the sacral base region.
The discs within the spine, separating the vertebrae, are under minimal mechanical load when bearing only compressive stresses resulting from the body""s weight. However, when the spine is flexed from its normal curvature, such as when standing erect with good posture, the discs then must bear additional compressive and/or tensile stresses due to forces applied by the muscles and ligaments in order to maintain the mechanical equilibrium when the spine is in a new flexed position. It should be noted that the payload on the neuro-muscular-skeletal (NMS) system is vastly different between sitting and lying down positions.
A great deal of spinal pain can be traced to excessive stresses applied to these discs and to the vertebral complex and the interrelated neuro-musculo-skeletal system. Consequently, developing an improved seating approach requires that one minimize neuro-musculo-skeletal stresses when the individual is in a sitting posture. When this is achieved, it will provide superior comfort and endurance to the occupant of a seat and provide significant benefit during extended sitting periods.
Many people must perform some function when in a seated position. If this were not the case then the goal of minimizing stresses on vertebral complex could be accomplished relatively simply by inclining the back portion of the seat away from the vertical position to more closely approximate spinal curvature positions when the person was erect. However, tasks must be performed while seated. This necessarily requires upper body motion. As such motion occurs, it will create varying degrees of stress throughout the neuro-musculo-skeletal system. This is caused by the movement of muscles and ligaments associated with the body motion as movement occurs when the body changes position. Related stresses can also be aggravated by movement, especially when compared with stresses found in a perfectly static seated posture. Motion moves the upper body from its center of gravity, or from an equilibrium position established by the vertebrae, muscles and ligaments holding each vertebrae in the system change position and move in response. As the center of gravity changes, and the equilibrium position changes, this also increases bending moments around each vertebrae and thus discs are placed under additional, though varying, stresses.
When seated the major portion of the upper body, and certainly its center of gravity, is positioned above the fixed end of the spine. When bending of the spine takes it out of its columnar position, and thus out of equilibrium, motion occurs about a joint between the fifth lumbar vertebrae and the sacrum. Consequently, one objective of the present invention to stabilize and correctly orient this lumbo-sacral joint. This is important in providing a functionally active and comfortable seated position where the sacral base is supported. In that condition sitting can be endured for sustained periods. More specifically, if a seating device is arranged so that the sacrum, and in particular the sacral base, is not securely positioned at an angle that allows the spine to support the weight born by the fifth lumbar vertebrae, without requiring additional bending and shear stresses to maintain equilibrium of the spine, then no amount of additional support of the occupant""s upper body will result in an optimally functional seat. It will also not provide sitting comfort for an extended time.
The present invention relates to a method and apparatus for supporting the lumbar lordoses of the spine to achieve a spinal shape similar to the shape found in a normal standing posture, but while seated. This is accomplished, in part, by securely locating a seated person""s pelvis in a position that will maintain good spinal posture while seated. First, the sacrum itself must be properly positioned by locating the sacrum along its posterior surface. This is done by applying pressure directly over the posterior surface of the sacrum, and principally to the upper one third of the sacrum, the sacral base. Secondly, the force generated by such a sacral pressure exerting device must be resisted through a combination of frictional, gravitational or other mechanical means in order to prevent movement of the person in an anterior direction across the surface of the seat or away from the sacral support and away from the supporting force.
The sacral support of the present invention is designed to position the sacrum but to do so in a way that permits the ability to also compress adjacent soft tissue in a variable manner. The present invention permits the option to adjust the specific pressure to the sacral base and to change the pressures per square inch at that region. Thus, it is possible to vary the intensity of the specifically applied pressure to the sacral base to thereby achieve the support of and/or movement of the sacrum in a posterior to an anterior direction. This pressure can be directed against the individual at an angle that can vary from, for example, 15-20 degrees, plus and minus from a direction perpendicular to the sacrum. The most effective direction or angle will depend upon a number of factors, such as, for example, the shape of the seat, the angle of the seat back relative to the seat bottom, and the size of the person. However, the present invention can provide the desired sacral support, in a sitting condition, regardless of what position the seat is adjusted to with regard to its angle of incline.
Support of the seated individual is important since the payload on the neuro-muscular-skeletal system is quite different between sitting and supine positions. That payload difference also dictates muscle function without substantially compressing the adjacent soft body tissue in order to maintain a desirable sacrum base angle. The posterior surface of the sacrum is a relatively flat surface and is covered only with a minimum amount of soft tissue and muscle. Thus, it is amenable to be oriented by placing it in close proximity to an orienting surface. This orienting surface will preferably maintain a desirable sacral base angle of from about 20xc2x0 to 50xc2x0 from the plane of a substantially horizontal seat, but corrected for inclination of the spinal column from vertical, or for back rest inclination.
Other objects, features, and characteristics of the present invention will become apparent upon consideration of the following description in the appended claims with reference to the accompanying drawings, all of which form a part of the specification, and wherein referenced numerals designate corresponding parts in the various figures.